A study of oxygen content in GaN, AlN, and GaAlN powders

A three-step solution-based method has been adopted and improved to synthesize AlN, GaAlN, and GaN powders with low oxygen content by sequential conversion of nitrates to hydroxides to fluorides and finally into nitrides. The synthesis parameters for rare-earth-activated AlN powders, high-purity single-phase GaN, and GaAlN were determined. Oxygen content of approximately 4 atom % in GaN as determined by energy-dispersive spectroscopy was achieved by optimizing the experimental process. X-ray diffraction observed single-phase AlN, GaN, and GaAlN powders; reflectance measurements indicated a slightly increased bandgap for the synthesized GaN powder with the highest purity compared to those with higher oxygen content, and the GaAlN powder with more incorporated aluminum.